| 摘要 |
PURPOSE:To stop a counter when comparison voltage changes from H level to L level, and to set initially a sound volume to 2<n>-stage resolution by only one terminal by comparing dividing voltage of a variable resistor with the voltage into which output value of a n-bit counter is DC-converted when throwing in power supply. CONSTITUTION:When throwing in power supply, the 1st and 2nd n-bit counters 1 and 7 start to count the basic clock F, and the comparator 10 compares the DC voltage which devided of a resistor 12 with output of the counter 7. When the DC voltage of the counter 7 is higher, input of the clock f into the counter 7 is stopped. The counted value of the counter 7 is inputted as data value into a n-bit up/down counter 6, and output of the counter 6 is equal to that of the counter 7. Outputs of the counter 1 and 6 are added to a coincidence circuit 2, the FF3 outputs pulse width modulated wave corresponding to data of the counter 7, and a terminal 14 outputs the same voltage as that which the resistor 12 devides to. |
